Antibacterial activities and conformations of synthetic α‐defensin HNP‐1 and analogs with one, two and three disulfide bridges

Mandal, Mahitosh; Nagaraj, Ramakrishnan

doi:10.1034/j.1399-3011.2002.01945.x

Cited by 67 publications

(58 citation statements)

References 47 publications

(89 reference statements)

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“…It has been shown that the cyclic analogs of HNP-1 with different SOS pairings exhibit antimicrobial activity, whereas linear HNP-1 is inactive (27). Thus, it is of interest to address whether these SOS bonds are essential for the function of HNP-1 as a LF inhibitor.…”

Section: Discussionmentioning

confidence: 99%

Human α-defensins neutralize anthrax lethal toxin and protect against its fatal consequences

Kim

Gajendran

Mittrücker

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

140

124

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Anthrax caused by Bacillus anthracis represents a major bioterroristic threat. B. anthracis produces lethal toxin (LeTx), a combination of lethal factor (LF) and protective antigen that plays a major role in anthrax pathogenesis. We demonstrate that human neutrophil ␣-defensins are potent inhibitors of LF. The inhibition of LF by human neutrophil protein (HNP-1) was noncompetitive. HNP-1 inhibited cleavage of a mitogen-activated protein kinase kinase and restored impaired mitogen-activated protein kinase signaling in LeTx-treated macrophages. HNP-1 rescued murine macrophages from B. anthracis-induced cytotoxicity, and in vivo treatment with HNP-1-3 protected mice against the fatal consequences of LeTx.defensin ͉ innate immunity ͉ Bacillus anthracis

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Section: Discussionmentioning

confidence: 99%

Human α-defensins neutralize anthrax lethal toxin and protect against its fatal consequences

Kim

Gajendran

Mittrücker

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

140

124

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“…It was shown earlier that peptides derived from the HNP-1 sequence without AYRIPA, but constrained by one or two disulfide bridges, have antibacterial activity (28). The residue G does not appear to play a crucial structural role, as its replacement with A does not diminish the activity.…”

Section: Discussionmentioning

confidence: 99%

“…HNP-1 was synthesized on 4-hydroxymethylphenoxymethyl resin (Applied Biosystems; 0.9 mmol/g) (28) with the cysteines protected by acetamidomethyl (46). The removal of acetamidomethyl was effected by Hg(II) acetate and ␤-mercaptoethanol treatment (28,46) followed by gel filtration on a Biogel P-2 column. HNP-1 was then oxidized in 20% dimethyl sulfoxide-water (42) at a peptide concentration of 0.2 to 0.4 mM.…”

Section: Methodsmentioning

confidence: 99%

Antibacterial Activity of Human Neutrophil Defensin HNP-1 Analogs without Cysteines

Varkey

Nagaraj

2005

Antimicrob Agents Chemother

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The antibacterial activity of human neutrophil defensin HNP-1 analogs without cysteines has been investigated. A peptide corresponding to the HNP-1 sequence without the six cysteines (HNP-1⌬C) exhibited antibacterial activity toward gram-negative and gram-positive bacteria. Truncated analogs wherein the nine N-terminal residues of HNP-1 and the remaining three cysteines were deleted (HNP-1⌬C18) or the G was replaced with A (HNP-1⌬C18A) also exhibited antibacterial activity. Substantial activity was observed for HNP-1⌬C and HNP-1⌬C18 in the presence of 100 mM NaCl, except in the case of Pseudomonas aeruginosa. The linear peptides were active in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), indicating that proton motive force was not essential for killing of bacteria by the peptides. In fact, in the presence of CCCP, the peptides were active against P. aeruginosa even in the presence of 100 mM NaCl. The antibacterial activity of HNP-1⌬C, but not that of the shorter, 18-residue peptides, was attenuated in the presence of serum. The generation of defensins without cysteines would be easier than that of disulfide-linked defensins. Hence, linear defensins could have potential as therapeutic agents.Mammalian defensins are a family of cationic antimicrobial peptides characterized by three disulfide bridges (13,22,35). They are expressed in granulocytes, monocytes, macrophages, and epithelial cells of the skin, intestines, and other tissues (2, 13, 39). Based on the pattern of disulfide bonding, mammalian defensins have been classified into ␣ and ␤ families. In another class named the -defensins, in addition to three disulfide bridges, the amino-and carboxyl-terminal ends are linked via an amide bond (13). In humans, ␣-defensins are produced in neutrophils and Paneth cells of the small intestine, while ␤-defensins are expressed by epithelial cells at various sites (13,22). The -defensins have been identified only in primates (13,19). The expression of defensins is constitutive as well as induced by infection and inflammation (13,22,23). Defensin biosynthesis and release have been observed to be regulated by microbial signals, developmental signals, and cytokines (13,14). Apart from their role as microbicidal agents, defensins have also been implicated as effective immune modulators in adaptive immunity (11, 54). They have potency to enhance phagocytosis, induce the activation and degranulation of mast cells, and indirectly regulate innate antimicrobial immunity by affecting the production of chemokines such as interleukin-8, interleukin-10, and tumor necrosis factor from different cells (3,24,53). Studies have also revealed the role of defensins in adaptive immunity, as reflected by their chemotactic effect on monocytes, T cells, and immature dendritic cells (5,32,35,43,48,54).Human neutrophil defensins (HNP-1 to HNP-4) are stored in azurophilic granules of the neutrophil. They are transferred to phagolysosomes upon phagocytosis to kill the ingested microbes (14, 15). The crystal structure of HNP-3 rev...

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“…In vitro effect of nisin on red blood cells (RBCs) The effect of nisin on RBCs was determined with freshly isolated rabbit erythrocytes (Mandal & Nagaraj 2002). Heparinized blood in isotonic PBS (35 mM phosphate buffer, 150 mM NaCl, pH 7.0) was initially centrifuged at 2000 g for 10 min to remove the buffy coat.…”

Section: In Vitro Studiesmentioning

confidence: 99%

Evaluation of antimicrobial peptide nisin as a safe vaginal contraceptive agent in rabbits: in vitro and in vivo studies

Reddy

Aranha²,

Gupta³

et al. 2004

Reproduction

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In the midst of the global epidemics of both unwanted pregnancies and sexually transmitted infections (STIs), options that provide protection are ideal. In the present study, nisin, a known antimicrobial peptide, was evaluated for safety and contraceptive potential in vitro and in vivo in the rabbit. A concentration of 400 mg nisin per ml was found to be spermicidal in vitro, and the effect was dose and time dependent. In vivo studies indicated that intravaginal application of 1 mg nisin blocked conception in rabbits. Repeated application of nisin (50 mg/animal per day) in rabbits for 14 consecutive days did not cause local inflammation or damage to the vaginal epithelium. In addition, the rate of diffusion of nisin into the blood via the vaginal mucosal epithelium, and its clearance from the circulation was found to be rapid. No treatment-related changes were observed in the reproductive performance of rabbits after cessation of treatment. Furthermore, no changes were observed in the gestation period, subsequent growth and survival of neonates in these animals. When male rats were given nisin orally for 13 consecutive weeks, no effect was observed on reproductive performance. The number of pups born, survival and growth of pups were unaltered. The affinity studies of nisin revealed that spermatozoa are more susceptible to nisin than red blood cells and vaginal epithelial cells. We suggest that nisin with spermicidal and antimicrobial properties could serve as a safe vaginal contraceptive for future therapeutic interventions in STIs.

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Antibacterial activities and conformations of synthetic α‐defensin HNP‐1 and analogs with one, two and three disulfide bridges

Cited by 67 publications

References 47 publications

Human α-defensins neutralize anthrax lethal toxin and protect against its fatal consequences

Human α-defensins neutralize anthrax lethal toxin and protect against its fatal consequences

Antibacterial Activity of Human Neutrophil Defensin HNP-1 Analogs without Cysteines

Evaluation of antimicrobial peptide nisin as a safe vaginal contraceptive agent in rabbits: in vitro and in vivo studies

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